Excessive soot from exhaust system, car is white, rear is covered with bits of soot ever since I purchased the vehicle in Aug 2010 till to day Aug 2011. Dealer stated noting is wrong because the "check engine" light is not on. On start up after overnight parked-there is a visible puff of black smoke. Vehicle had 2800 miles, the dealer told me that it needed to be driven, so I drove 2000 miles in a week, it made no sense to me and it did not make a difference. A Chevy dealer told me he has had similar complaints on traverse model (same engine) but they cannot figure it out. I'm a former wheel vehicle maintenance officer us army, this is not normal for an engine exhaust to emit soot. It is a sign that there is unburned fuel in the cylinders. I average 14.5 mpg. And I believe there is a fuel leak or fuel bypass into the cylinders when the vehicle is parked due to the pressurized fuel system or just too much fuel that is not efficiently burned being allowed to enter the engine.

- Pineville, NC, USA

The contact owns a 2010 GMC Acadia. While the contact started the ignition a substantial amount of blue and black smoke emitted from the rear exhaust tail pipe for 35-40 seconds. The vehicle was taken to an authorized dealer where they informed him that the vehicle functioned as designed. The approximate failure mileage was 34.

- Graham, NC, USA